Berlin 2005 – scientific programme

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HL: Halbleiterphysik

HL 14: Heterostrukturen

HL 14.1: Talk

Friday, March 4, 2005, 15:00–15:15, TU P-N229

Route to Bose-Einstein condensation of excitons in coupled quantum wells — •Roland Zimmermann — Institut für Physik der Humboldt-Universität zu Berlin

Spatially indirect excitons in coupled quantum wells (CQW) exhibit extremely long radiative lifetimes and a strong mutual repulsion of dipolar character. In a recent experiment [1] with a lateral trap potential, a substantial blue shift (5 meV) of the exciton emission line combined with a narrow angular characteristic normal to the quantum well plane has been reported. We present first theoretical results to explain these novel findings. For the CQW we calculate both the direct and exchange potential which enter the spin-dependent exciton Hamiltonian [2] and apply a dynamical T-matrix approach for the exciton propagator. The calculated emission is blue shifted but spectrally broad due to exciton-exciton scattering. The angle-resolved emission exhibits a sharp spike, which is a direct manifestation of off-diagonal long range order evolving at low temperatures.

[1] D.W. Snoke et al., arXiv:cond-mat/0410298 (2004)

[2] S. Ben-Tabou de-Leon and B. Laikhtman, Phys. Rev. B 63, 125306 (2001)